Brake actuation assembly

ABSTRACT

An emergency braking system for use in connection with a drive apparatus including a drive belt and pulley system for transferring power from a prime mover to a transmission or transaxle. The braking system includes a pulley engaged to the drive belt and a spring engaged to the pulley to provide a bias force thereto. When tension from the belt is removed from the pulley, the spring forces the pulley into engagement with an actuator to engage a brake mechanism.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/057,874, filed Mar. 28, 2008, which claims the priority of U.S.Provisional Patent Application Ser. No. 60/909,789 filed on Apr. 3,2007. The prior applications are incorporated herein by reference intheir entirety.

BACKGROUND OF THE INVENTION

This invention relates to powered vehicles, including a brake and anemergency brake actuation assembly for use in connection therewith. Theinvention is disclosed herein in connection with a zero-turn mowerdevice including two hydrostatic transmissions powered by a prime mover.It will be understood that other embodiments could be used in connectionwith the inventions disclosed herein.

SUMMARY OF THE INVENTION

This invention discloses a system by which the brake mechanism of abelt-driven hydrostatic transaxle or other drive device may be activatedautomatically in the event the drive belt breaks during operation. Aswill be understood, transaxles such as those shown herein will generallyhave a brake mechanism used as a parking brake, and such brakes aregenerally not intended for use as a dynamic brake. Dynamic braking isusually provided by the hydraulic system and the user may alter theoutput of the hydraulic apparatus to effectively brake the vehicle. Suchhydrostatic transaxles including a parking brake mechanism aredisclosed, for example, in commonly owned U.S. Pat. Nos. 6,672,058 and6,775,976, the terms of which are incorporated herein by reference,including in particular the details of the brake and hydraulictransmission. It will be understood, however, that while this inventionis described herein as being used with a parking brake, the invention isnot so limited and could be used with other brake mechanisms.

When the drive belt for such a drive apparatus breaks during operation,the vehicle can free wheel down a slope. If the operator strokes thecontrols to neutral, the normal hydraulic braking will slow the vehicle.If the operator over-corrects by stroking the controls in the oppositedirection, the vehicle can continue to free wheel. At that moment,though, the operator may not consider applying the parking brake, as itis normally not used during vehicle operations. Thus, a need for anautomatic braking system is presented to provide for emergency brakingin such a situation, and the present invention provides such a system.

A better understanding of the objects, advantages, features, propertiesand relationships of the invention will be obtained from the followingdetailed description and accompanying drawings which set forth anillustrative embodiment and is indicative of the various ways in whichthe principles of the invention may be employed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view of a vehicle incorporating an embodimentof the brake apparatus in accordance with the principles of the presentinvention, with certain elements removed for clarity.

FIG. 2 is a top plan view of a portion of the vehicle of FIG. 1 showingthe frame and other components, with certain elements removed forclarity.

FIG. 3 is an elevational view of the components of a brake mechanism inaccordance with the principles of the present invention, with theemergency brake actuator in the non-activated position.

FIG. 4 is a view similar to FIG. 3 with the emergency brake actuator inthe activated position.

FIG. 5 is a top plan view of the actuator of FIG. 3 with the emergencybrake actuator in the non-activated position.

FIG. 6 is a view similar to FIG. 5 with the emergency brake actuator inthe activated position.

FIG. 7 is a view similar to FIG. 5, with the emergency brake actuator inan operative position between the fully activated and the non-activatedpositions.

FIG. 8 is a side elevational view of an alternative embodiment of thepresent invention.

FIG. 9 is a plan view of the embodiment shown in FIG. 8.

DETAILED DESCRIPTION OF THE DRAWINGS

The description that follows illustrates and exemplifies one or moreparticular embodiments of the present invention in accordance with itsprinciples. This description is not provided to limit the invention tothe embodiments described herein, but rather to explain and teach theprinciples of the invention in such a way to enable one of ordinaryskill in the art to understand these principles and, with thatunderstanding, be able to apply them to practice not only in theembodiments described herein, but also other embodiments that may cometo mind in accordance with these principles. The scope of the presentinvention is intended to cover all such embodiments that may fall withinthe scope of the appended claims, either literally or under the doctrineof equivalents.

FIG. 1 shows a vehicle 10 incorporating a first embodiment of thepresent invention. As shown in FIGS. 1 and 2, vehicle 10 is a mowingvehicle, which includes a prime mover 18, a frame 22, a set of pivotablefront casters 24 and a mower deck 26. Vehicle 10 also includes a pair oftransaxles or transmissions 12L and 12R that independently drive a pairof output axles 14, which in turn, each drive one of a pair of wheels 16that provide motion to vehicle 10. While the embodiment shown anddescribed herein utilizes hydrostatic transmissions, this invention isalso applicable to other types of drive systems, such as, for example,continuously variable drive systems, continuously variable transmissions(CVTs) and hydraulic drive systems with a variable pump or motor.Accordingly, the terms “transmission” and “transaxle” are used hereinfor convenience and are not used to limit the present invention.Furthermore, although a mowing vehicle is shown in FIG. 1, the presentinvention can be applied to other vehicle types as well. A drive pulley28 is mounted on and driven by output shaft 19 of prime mover 18, and abelt 27 is used to connect drive pulley 28 with transaxle pulleys 29 aand 29 b.

A pair of transaxles 12L, 12R are mounted on frame 22, each comprising atransaxle housing 30, 32 and an output axle 14 to drive one of the rearwheels 16 of mower 10. In the depicted embodiment, transaxles 12L, 12Rare similar to those depicted in commonly owned U.S. Pat. No. 7,134,276,the terms of which are incorporated herein by reference, including inparticular the details of the hydraulic transmission disclosed therein.Transaxles 12L, 12R are intended to be internally identical, and canalso be externally identical but for the brake actuation mechanism asdescribed herein. Thus, the description herein will focus on transaxle12L, on the left side of mower 10 as shown in FIG. 2, and theelevational view of FIG. 1 has transaxle 12R removed so that one can seethe external structure of transaxle 12L, including emergency brakeactuation mechanism 40, in greater detail.

In the embodiment depicted in FIGS. 1, 2 and 3, brake linkage 36 a isintended to activate an internal brake (not shown) in transaxle 12L, andmovement of brake linkage 36 a to the right in FIG. 3 will activate thebrake by rotating pivot rod 54 for this internal brake. Linkage 36 aalso includes a slot 37 in one end thereof to engage a fastener 43 csecured to brake arm 52, so that movement of linkage 36 a to the rightin FIG. 3 will cause rotation of brake arm 52 clockwise about the pivotpoint through fastener 43 d. Bias spring 56 also acts to retain brakearm 52 in the deactivated position. It will be understood thatadditional linkages will be used to connect linkages 36 a, 36 b to theappropriate foot pedal or hand control (not shown) on vehicle 10; suchadditional linkages are not depicted for clarity.

Slot 35 in clamp arm 34 permits the activation of brake arm 52 bymovement of linkage 36 a without movement of clamp arm 34 and thereforewithout the activation of emergency brake mechanism 40. Similarly, slot37 in linkage 36 a also permits the emergency brake mechanism 40 to beactivated, as will be described below, without moving linkage 36 a.

As will be understood, pulley 29 a is connected to an input shaft (notshown) to drive an internal hydraulic pump (not shown). This hydraulicpump could be of the axial piston type such as is shown in U.S. Pat. No.7,134,276 previously referenced, but the particular type of pump orhydrostatic transmission is not critical to this invention. Pulleys 29a, 29 b are thus used to respectively drive transaxles 12L, 12R, and arepowered by belt 27 driven by drive pulley 28. As is generally known, anidler pulley 42 is also used to engage belt 27 to provide theappropriate tension in the belt. FIGS. 1, 2 and 3 show this arrangementduring normal operation.

The emergency brake mechanism 40 comprises a moveable assembly includingswing arm 60 on which idler pulley 42 is mounted by means of a fastener43 a; swing arm 60 pivots about the point at which a fastener 43 bconnects swing arm 60 to transverse frame member 22 a. Swing arm 60 andidler pulley 42 are retained in the operative mode as shown in, e.g.,FIG. 3 by the tension of belt 27. It will be understood that the termfastener is being used generically herein, and various means ofconnecting these elements can be used, along with sleeves, spacers andthe like that may be depicted but need not be described for one of skillin the art.

Emergency brake mechanism 40 further comprises clamp arm 34 which iscapable of engaging brake arm 52 and forcing rotation of brake arm 52clockwise to activate the braking system. Spring 38 is secured to clamparm 34 and to a connection point or bracket 33 secured to transaxlehousing 30. Any fixed structure could be used for this connection;spring 38 biases clamp arm 34 toward the activated position shown inFIG. 4. Clamp arm 34 is held in the deactivated position, as shown inFIG. 3, by means of a transverse rod 48 fixed to release arm 46 to forma latching mechanism of the over-center design. Rod 48 is held in pocket31 formed on transaxle housing 30 and extends to a similar pocket (notshown) in the opposite transaxle housing 32 so that the brake mechanismon both transaxles are simultaneously engaged. Rod 48 engages recess 45formed in clamp arm 34 so that clamp arm 34 is held in the deactivatedposition as shown in FIG. 3.

Emergency brake mechanism 40 further comprises a striker 62 attached toand moveable with idler pulley 42. Spacer 67 may be used to separateidler pulley 42 from striker 62. Tension spring 58 acts as a bias memberto provide a bias force to swing arm 60. Spring 58 is engaged to idlerpulley swing arm 60 and is also secured to bracket 64 and pin 65 in amanner so that a spring force is applied to swing arm 60. As notedpreviously, idler pulley 42 and swing arm 60 are held in the operativeposition (FIGS. 2 and 3) by belt 27. If belt 27 breaks, however, spring58 pulls idler pulley 42 to cause rotation of swing arm 60 about itspivot axis, thereby causing striker 62 to contact release arm 46 withsufficient force to rotate release arm 46 and transverse rod 48 aboutthe longitudinal axis of rod 48.

Release arm 46 is secured to clamp arm 34 by means of a pivot jointfastener 43 f, so that as release arm 46 rotates from the position inFIG. 3, clamp arm 34 is raised, to the position in FIG. 7, therebylifting clamp arm 34 off transverse rod 48. This movement causes clamparm 34 to be released from its over center-latched position, and theforce of clamp arm spring 38 pulls clamp arm 34 to the right in FIG. 3.A fastener 43 e and a pair of washers 44 on opposite sides of clamp arm34 provide the engagement between slot 35 on clamp arm 34 and brake arm52. Note that one of the washers 44 is not depicted in these figures forclarity. Thus, as clamp arm 34 is pulled to the right, slot 35 engagesbrake arm 52 and causes it to rotate clockwise, thereby rotating brakepivot rod 54 to cause braking of the system, as described previously.

As noted previously, emergency brake mechanism 40 used on secondtransaxle 12R is substantially the same as described above, as therotation of transverse rod 48 will trigger movement of a similar clamparm 34, to which rod 48 is similarly secured. This action will activatea second brake (not shown) internal to second transaxle housing 32 sothat braking is provided to both transaxles 12L and 12R at the sametime. Thus, it can be seen that a single emergency brake actuationmechanism 40 is used to actuate the brakes on both transaxles.

Depending on the vehicle application, additional vehicle framestiffening members may be required to prevent the flexing of the vehicleframe during operation from damaging transverse rod 48.

The alternative embodiment shown in FIGS. 8 and 9 modifies the structureof release arm 46 to separate its functions of rotating transverse rod48 and lifting clamp arm 34 out of the over-center position into twoseparate elements. Specifically, in this embodiment, when striker 162hits release arm 146 causing rotation of transverse rod 148, suchrotation is transferred to a separate link 141 which is engaged to clamparm 134. Transverse rod 148 is located in a pocket 134 in housing 130and in a similar pocket in the other transaxle housing (not shown) toengage the emergency brake mechanism of the second transaxle in asimilar manner. When clamp arm 134 is lifted out of its over-centerposition, the structure shown in FIGS. 8 and 9 operates identically tothat in the prior embodiment, thus causing rotation of brake arm 152.The other elements of this embodiment can be identical to thosedescribed previously. This separation of link 141 and release arm 146provides additional flexibility in terms of the location of suchelements with respect to transverse rod 148. The distance permittedbetween these two elements is restricted by factors such as the amountof flex that would be introduced to transverse rod 148 by the distancebetween release arm 146 and clamp arm 134.

While specific embodiments of the invention have been described indetail, it will be appreciated by those skilled in the art that variousmodifications and alternatives to those details could be developed inlight of the overall teachings of the disclosure. Accordingly, theparticular arrangement disclosed is meant to be illustrative only andnot limiting as to the scope of the invention which is to be given thefull breadth of the appended claims and any equivalents thereof.

The invention claimed is:
 1. A drive apparatus, comprising: a primemover and a first pulley powered by the prime mover; a transmissioncomprising a housing and an input shaft having an external end disposedoutside the housing; a second pulley disposed on the input shaft; a beltconnecting the first and second pulleys to transmit force from the primemover to the transmission; a brake mechanism comprising a rotatablepivot rod having one end external to the housing, wherein the pivot rodrotates about its longitudinal axis, and a brake arm assembly disposedexternal to the housing for engaging and rotating the pivot rod, thebrake arm assembly having a first position where the brake mechanism isengaged and a second position where the brake mechanism is disengaged; afirst bias member engaged to the brake arm assembly and providing afirst spring force for biasing the brake arm assembly toward the firstposition; a movable assembly engaged to the belt, and comprising acontact member, whereby tension from the belt retains the contact memberin a position away from the brake arm assembly; and a second bias memberengaged to the movable assembly and providing a second spring force tobias the contact member towards the brake arm assembly, whereby whentension from the belt is removed from the movable assembly, the secondbias member forces the contact member into engagement with the brake armassembly to actuate the brake mechanism.
 2. The drive apparatus of claim1, wherein the brake arm assembly comprises a brake arm member fixed toand pivotable with the one end of the pivot rod.
 3. The drive apparatusof claim 2, wherein the brake arm assembly further comprises a clamp armoperatively engaged to the brake arm member, whereby movement of theclamp arm from a first position to a second position causes the brakearm member to rotate the pivot rod.
 4. The drive apparatus of claim 3,wherein the clamp arm is retained in the first position by anover-center mechanism comprising a recess formed in the clamp arm and atransverse rod extending from the housing and engaged to the recess whenthe clamp arm is in the first position.
 5. The drive apparatus of claim4, wherein the brake arm assembly further comprises a release armengaged to the transverse rod and rotatably fixed to one end of theclamp arm, whereby, when the tension from the belt is removed from themovable assembly, the contact member engages the release arm to causethe release arm to pivot about a longitudinal axis of the transverserod, thereby lifting the clamp arm recess off the transverse rod.
 6. Thedrive apparatus of claim 3, further comprising a linkage connected tothe brake arm member and to a user control, and the clamp arm comprisesa slot to permit operation of the brake mechanism independent of themovable assembly.
 7. The drive apparatus of claim 6, wherein the linkagecomprises a second slot to permit operation of the brake mechanismindependent of the user control.
 8. The drive apparatus of claim 2,wherein the first bias member comprises a first spring and the secondbias member comprises a second spring.
 9. The drive apparatus of claim8, further comprising a third spring engaged to the brake arm member tobias the brake arm assembly to the second position.
 10. The driveapparatus of claim 3, further comprising a linkage connected to thebrake arm assembly and to a user control, and a slot formed in thelinkage to permit operation of the brake mechanism independent of theuser control.
 11. The drive apparatus of claim 5, wherein the releasearm consists of a single member directly engaged to the one end of theclamp arm.
 12. The drive apparatus of claim 1, wherein the movableassembly further comprises an idler pulley engaged to the belt.
 13. Thedrive apparatus of claim 1, wherein the transmission comprises ahydraulic transmission.
 14. A vehicle having a prime mover disposed on avehicle frame, comprising: at least a first transmission providingoutput to a vehicle axle and comprising a brake mechanism; a drive beltand pulley system for transferring power from the prime mover to thefirst transmission; an idler pulley mechanism comprising an idler pulleyengaged to the drive belt and retained in a first position by tensionfrom the drive belt; a pivot rod having a longitudinal axis of rotationfor actuating the brake mechanism; and an emergency brake actuator,comprising: a brake arm assembly engaged to one end of the pivot rod forcausing rotation of the pivot rod, the brake arm assembly having a firstposition where the brake mechanism is engaged and a second positionwhere the brake mechanism is disengaged; a first bias member engaged tothe brake arm assembly for biasing the brake arm assembly toward thefirst position; an actuator connected to the brake arm assembly; and asecond bias member engaged to the idler pulley mechanism, whereby whentension from the drive belt is removed from the idler pulley, the secondbias member forces the idler pulley mechanism into engagement with theactuator.
 15. The vehicle of claim 14, further comprising a secondtransmission providing output to a second vehicle axle and comprising asecond brake mechanism; a transverse rod extending from the firsttransmission to the second transmission; and a second emergency brakeactuator engaged to the second transmission and comprising a secondbrake arm assembly, wherein engagement of the idler pulley mechanismwith the actuator rotates the transverse rod to actuate the second brakemechanism.
 16. A drive apparatus, comprising: a prime mover and a firstpulley powered by the prime mover; a transmission comprising a housing,an input shaft, a second pulley disposed on the input shaft, and a brakemechanism comprising a rotatable pivot rod having one end external tothe housing, wherein the pivot rod rotates about its longitudinal axis;a brake arm disposed external to the housing for engaging the one end ofthe pivot rod, the brake arm having a first position where the brakemechanism is engaged and a second position where the brake mechanism isdisengaged; a belt connecting the first pulley to the second pulley totransmit force from the prime mover to the input shaft; a first biasmember for biasing the brake arm to the first position; a second armengaged to the brake arm and capable of rotating the brake arm; anemergency brake assembly engaged to the belt, whereby tension from thebelt retains the emergency brake assembly in a first, disengagedposition; the emergency brake assembly further comprising a second biasmember to bias the emergency brake assembly towards a second, engagedposition, whereby when tension from the belt is removed from theemergency brake assembly, the second bias member forces the emergencybrake assembly to the second position which causes the brake arm torotate to its first position where the brake mechanism is engaged.
 17. Avehicle, comprising: a prime mover driving an input pulley connected toa drive belt; a first transmission driving a first wheel of the vehicle,the first transmission comprising a first housing, a first input shaft,a first drive pulley disposed on the first input shaft and driven by thedrive belt, and a first brake arm located external to the first housingand movable between an engaged position and a disengaged position; afirst emergency brake actuator disposed external to the firsttransmission and engaged to the first brake arm; a second transmissiondriving a second wheel of the vehicle, the second transmissioncomprising a second housing, a second input shaft, a second drive pulleydisposed on the second input shaft and driven by the drive belt, and asecond brake arm located external to the second housing, and movablebetween an engaged position and a disengaged position; a secondemergency brake actuator disposed external to the second transmissionand engaged to the second brake arm; and a release member capable ofactuating both the first and second emergency brake actuators when apredetermined condition is met, without any input from an operator ofthe vehicle.
 18. The vehicle of claim 17, wherein the predeterminedcondition is the breakage of the drive belt.
 19. The vehicle of claim18, further comprising a movable assembly engaged to the drive belt andmoveable between a first position and a second position, whereby tensionfrom the drive belt retains the movable assembly in the first position,the movable assembly further comprising a contact member and a biasmember engaged to the movable assembly to bias the movable assemblytowards the second position whereby, when tension from the drive belt isremoved from the movable assembly, the bias member forces the contactmember into engagement with the release member to engage the first andsecond emergency brake actuators.
 20. The vehicle of claim 18, whereinthe first emergency brake actuator comprises a first clamp arm disposedexternal to the first housing and operatively engaged to the first brakearm, whereby movement of the first clamp arm from a first position to asecond position causes the first brake arm to move to the engagedposition; and the second emergency brake actuator comprises a secondclamp arm disposed external to the second housing and operativelyengaged to the second brake arm, whereby movement of the second clamparm from a first position to a second position causes the second brakearm to move to its engaged position.
 21. The vehicle of claim 19,wherein the movable assembly comprises an idler pulley engaged to thedrive belt.
 22. The vehicle of claim 19, wherein the first and secondtransmissions comprise hydraulic transmissions and the bias membercomprises a spring.
 23. The vehicle of claim 17, further comprising afirst brake linkage engaged to the first brake arm to permit a vehicleoperator to move the first brake arm to its engaged position and asecond brake linkage engaged to the second brake arm to permit thevehicle operator to move the second brake arm to its engaged position.